DHAKA (AFP) - Bangladesh on Sunday ordered an enquiry into a plastics factory fire that killed 13 workers, the latest in a series of accidents that have highlighted appalling conditions in the country's workplaces.

A five-man government team will investigate whether the Nasim Plastics factory - housed in a four-storey building in the Dhaka suburb of Mirpur - had a proper operating licence, fire equipment and statutory safety features. "The probe team will file a report on their findings in three days. We want to find out what caused this accident," said Mr Syed Ahmed, head of the factory inspection department.

Police and fire officers believe last Saturday's blaze started when gas cylinders exploded in the boiler room, then raced through the four-storey building in minutes. The walls of the factory collapsed due to the explosion.

Three workers are critically ill in hospital with burns, the police said. The 13 who died were burnt to death or suffocated after they were trapped on the upper floors, they said. More than a dozen people suffered minor burns.

Factory fires are common in impoverished Bangladesh, which is emerging as a new hub for labour-intensive industries. Many plants have poor safety standards and lack fire-fighting equipment.

In November 2012, 111 garment workers were killed when a blaze devastated a nine-storey garment factory outside Dhaka.

In April 2013, the Rana Plaza garment factory complex collapsed, leaving 1,138 people dead and sparking a global outcry over the country's workplace safety standards.

Western retailers such as H&M and Carrefour, which buy billions of dollars of clothing from Bangladesh every year, launched a campaign to improve safety standards in the country's thousands of garment factories.

Although inspectors hired by the retailers and the government have probed more than two thousand export-oriented factories, thousands more remain uninspected, authorities said.

"We're trying to ensure safety issues in all of the country's factories including the ready-made garment factories," said Mr Ahmed, adding the government has this year more than doubled the number of factory inspectors.